Closing spring adjusting means for a fuel injection valve

ABSTRACT

A fuel injection valve which includes a valve needle urged against a valve seat by a closing spring which is disposed between a fixed part of the valve and a spring seat disc supported by a nut threadedly secured to the stem of the valve needle. For varying the preload of the spring, the valve needle is rotated, whereby said nut is axially displaced changing the extent to which said spring is compressed.

United States Patent Inventor Rudolf Kraus Stuttgart-Giebel, Germany Appl. No. 871,865 Filed Oct. 28, 1969 Patented Oct. 19, 1971 Assignee Robert Bosch GmbH Stuttgart, Germany Priority Nov. 23, 1968 Germany P 18 10 544.7

CLOSING SPRING ADJUSTING MEANS FOR A FUEL INJECTION VALVE 6 Claims, 2 Drawing Figs.

U.S. Cl 239/453, 239/571, 239/533 Int. Cl B05b 1/32 Field of Search 239/452,

[56] References Cited UNITED STATES PATENTS 2,035,203 3/1936 Smith 239/452 X 2,975,982 3/1961 Dahl 239/453 FOREIGN PATENTS 1,032,162 3/1953 France 239/533 819,607 9/1959 Great Britain 239/533 Primary Examiner-Llod L. King Assistant Examiner-John J. Love Attorney- Edwin E. Greigg ABSTRACT: A fuel injection valve which includes a valve needle urged against a valve seat by a closing spring which is disposed between a fixed part of the valve and a spring seat disc supported by a nut threadedly secured to the stem of the valve needle. For varying the preload of the spring, the valve needle is rotated, whereby said nut is axially displaced changing the extent to which said spring is compressed.

minnow 19 ml 3.513.998

M V 5 //VVE/V70/? Penal/1424055 6/15 Arr-04 w CLOSING SPRING ADJUSTING MEANS FOR A FUEL INJECTION VALVE BACKGROUND OF THE INVENTION This invention relates to a valve, particularly a fuel injection valve of the type adapted for the injection of fuel into the suction tube of internal combustion engines. The fuel injection valve is further of the type that includes a valve needle adapted to open in the direction of the fluid flow against the force of a closing spring. The stem portion of the valve needle extends through the nozzle body and projects into a cavity of a nozzle holder, where its terminus is connected with the spring seat disc of a closing spring by turnable means adapted to vary the tension of said spring.

In known fuel injection valves of the aforenoted type (such as disclosed in U.S. Pat. No. 2,096,581) the spring seat disc is provided with a threaded bore, which directly receives the threaded stem of a valve needle. In order to ensure that the valve needle does not turn with respect to the spring seat disc during operation, there is provided a lock nut disposed in axial alignment with the valve needle and received by an opposing thread provided in the valve plate of the valve needle. This known structure has the disadvantage that every time the preload of the closing spring is to be changed, the fuel injection valve has to be taken apart and the locknut loosened. At the same time, the valve plate has to be securely held against turning by means of a particular device. Only upon completing these steps may the valve needle be turned with respect to the spring seat disc for changing the preload (i.e. the force) of said spring. Subsequently, the locknut has to be tightened, the auxiliary securing device removed and the fuel injection valve reassembled.

OBJECT AND SUMMARY OF THE INVENTION It is a primary object of the invention to provide an improved fuel injection valve from which the aforenoted disadvantages are eliminated.

Briefly stated, according to the invention, the aforenoted turnable means comprises an internally threaded polygonal nut supports the spring seat disc and which is secured against rotation by inner wall faces of the nozzle holder complemental with said polygonal nut. A rotation of the valve needle effected by a tool externally engaging the same, causes an axial displacement of said nut, changing thereby the extentto which said spring is compressed.

The invention will be better understood as well as further objects and advantages will become apparent from the ensuing detailed specification of a preferred, although exemplary, embodiment of the invention taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is an axial sectional view of the fuel injection valve according to the invention, and

FIG. 2 is a sectional view taken along line II-II of FIG. 1.

DESCRIPTION OF THE EMBODIMENT Turning now to FIG. I, there is shown a nozzle holder 1 provided with an axial bore 2 in which there is disposed a filter element 3. Downstream of the filter element 3, the bore 2 is enlarged to form a chamber 4 in which there are disposed the working parts of the fuel injection valve. The chamber 4- is, at its downstream end, closed by a nozzle body 5 provided with an axial bore 6.

A valve needle generally indicated at 7 is disposed with respect to the nozzle body 5 and nozzle holder I in such a manner that the stem 7a of the valve needle extends through bore 6 and projects into chamber 4, while the hemispherical head 8 of the valve needle is arranged externally of the nozzle body 5 and is adapted to engage a complementally formed valve seat 5a.

0n the threaded terminal portion of the valve stem 7a remote from the valve head 8 there is mounted a hexagonal nut 9 serving as a support for a spring seat disc 10 and a spring 11 which, with its other end, engages a radial shoulder 5b of the nozzle body 5. Within the hexagonal nut 9 there is disposed a resilient, preferably plastic, insert 12 having a central bore surrounding valve stem 7a in a tight fit. By virtue of the frictional contact between stem 70 and insert 12, the valve needle 7 is prevented from accidental rotation with respect to the nut 9.

Referring now to FIG. 2, at a location radially adjacent to the hexagonal nut 9, diametrically opposed wall portions of nozzle holder 1 are flattened as shown at 13. As a result, the internal planar faces of these wall portions prevent the nut 9 from rotating.

For varying the preload and thus the force of closing spring 1 l, a polygonal extension 14; of the valve head 3 is engaged by a suitable tool, such as a socket wrench, or the like. As the frictional forces exerted by insert 12 on stem 7a are overcome by the torque applied to the tool, the valve needle 7 rotates with respect to the hexagonal nut 9. The latter is prevented from turning with the rotating nut 9 by means of planar wall portions 13. As a result, the hexagonal nut 9 is axially displaced with respect to the radial shoulder 5b of the nozzle body 5 and thus, the extent of compression or preload of closing spring II is changed.

As well seen in FIG. I, the valve needle 7 is disposed in bore 6 of the nozzle body 5 with a loose fit, so that an annular passageway is obtained through which the fuel may flow after the unseating of valve needle 7. Also, due to said loose fit, the bore 6 does not guide the valve needle 7 in its reciprocating motion, so that the latter is selfcentering as it assumes its closed (seated) position. In order to ensure that said selfcentering is not disturbed by an axially asymmetrical force caused, for example, by an inaccurate terminal plane of spring I 1, the engaging faces of the hexagonal nut 9 and those of the spring seat disc 10 have a complemental, spherical configuration.

When assembling the aforedescribed fuel injection valve, first the movable valve parts, that is, the hexagonal nut 9, the spring seat disc 10, the spring 11 and the valve needle 7 are assembled with the nozzle body 5. Thereafter, the nozzle body 5 is inserted into the nozzle holder ll, so that an internal shoulder 15 thereof abuts against the radial shoulder 5b of the nozzle body 5. Thereafter, the sleevelike terminal portion of the nozzle holder 1 is crimped over an edge 16 of the nozzle body 5.

That which is claimed is:

I. In a valve, particularly fuel injection valve of the known type that includes (A) a nozzle holder, (B) a valve needle formed of a valve stem and a valve head, (C) a valve seat, (D) a spring, (E) a spring seat disc engaged by one end of said spring, and (F) means threadedly secured to said valve stem and supporting said spring seat disc, said means being turnable to vary the preload of said spring urging said valve head into a closed position against said valve seat, the improvement comprising,

A. a nut threadedly secured to said valve stem and constituting said turnable means and B. complemental means forming part of said nozzle holder and said nut to prevent the latter from rotating with respect to the nozzle holder when said valve needle is turned with respect to said nut.

2. An improvement as defined in claim I, wherein said complemental means is formed of at least one pair of diametrically opposed planar external faces of said nut and of at least one pair of diametrically opposed planar internal faces of said nozzle holder.

3. An improvement as defined in claim 2, wherein said nut is of the polygonal type.

4. An improvement as defined in claim 2, wherein said diametrically opposed planar internal faces form part of flattened wall portions of said nozzle holder.

sert is provided with a throughgoing bore surrounding said valve stem with a tight fit, said insert is made of resilient material to frictionally and yieldingly engage said valve stem. 

1. In a valve, particularly fuel injection valve of the known type that includes (A) a nozzle holder, (B) a valve needle formed of a valve stem and a valve head, (C) a valve seat, (D) a spring, (E) a spring seat disc engaged by one end of said spring, and (F) means threadedly secured to said valve stem and supporting said spring seat disc, said means being turnable to vary the preload of said spring urging said valve head into a closed position against said valve seat, the improvement comprising, A. a nut threadedly secured to said valve stem and constituting said turnable means and B. complemental means forming part of said nozzle holder and said nUt to prevent the latter from rotating with respect to the nozzle holder when said valve needle is turned with respect to said nut.
 2. An improvement as defined in claim 1, wherein said complemental means is formed of at least one pair of diametrically opposed planar external faces of said nut and of at least one pair of diametrically opposed planar internal faces of said nozzle holder.
 3. An improvement as defined in claim 2, wherein said nut is of the polygonal type.
 4. An improvement as defined in claim 2, wherein said diametrically opposed planar internal faces form part of flattened wall portions of said nozzle holder.
 5. An improvement as defined in claim 1, including an insert disposed in said nut to prevent accidental rotation of said valve needle with respect to said nut.
 6. An improvement as defined in claim 5, wherein said insert is provided with a throughgoing bore surrounding said valve stem with a tight fit, said insert is made of resilient material to frictionally and yieldingly engage said valve stem. 